Internal combustion engine with steam expansion stroke

Abstract

A method for controlling an internal combustion engine, and an internal combustion engine, having at least one cylinder ( 1 ), a reciprocating piston ( 16 ) arranged in the cylinder ( 1 ), a combustion chamber ( 15 ) delimited by the cylinder ( 1 ) and the piston ( 16 ), and inlet and outlet valves ( 2, 3 ) that are controlled by a computer-based control system ( 5 ). The combustion engine includes elements ( 10 ) for injecting water or water steam into the combustion chamber ( 15 ), and the control system ( 5 ) is arranged to control the inlet and outlet valves ( 2, 3 ) and the elements ( 10 ) for injection of water or water steam such that power strokes that are mainly based on expanding combustion gases are alternated with power strokes that are mainly based on expanding water steam.

1. A method for controlling internal combustion engines, by which power strokes that are mainly based on expanding combustion gases are alternated with power strokes that are mainly based on expanding water steam, for the purpose of transforming into work the heat that upon combustion is generated in the cylinder and in the exhaust gases, water and/or water steam being supplied to a combustion chamber ( 15 ) in connection to the end of an evacuation stroke, characterised in that the engine comprises controllable valves ( 2 , 3 ), the control of which is based on an electronic control system, which is based on a computer program, and that inlet valves to the combustion chamber are closed as an answer to the control system delivering a signal that indicates that water/water steam is to be supplied to the combustion chamber ( 15 ). 
     
     
       2. A method according to  claim 1 , characterised in that a supply of water cools the top of a reciprocating piston ( 16 ) in a cylinder ( 1 ) as well as hot surfaces that delimit the combustion chamber ( 15 ), the water being evaporated as it gets into contact with the hot surfaces. 
     
     
       3. A method according to  claim 1 , characterised in that supplied water steam is generated by evaporation of water by means of exhaust gas heat. 
     
     
       4. A method according to  claim 3 , characterised in that the temperature of water that is supplied to the combustion chamber ( 15 ) is adapted for the purpose of obtaining an immediate evaporation as it is introduced into the combustion chamber or as it gets in contact with heat surfaces in the latter. 
     
     
       5. A method according to  claim 1 , characterised in that an exhaust gas system connected to the engine is insulated for the purpose of decreasing exterior cooling of the exhaust gases therein by the environment. 
     
     
       6. A method according to  claim 1 , characterised in that the cylinder or cylinders ( 1 ) of the engine is/are insulated in order to decrease exterior cooling of said cylinder or cylinders ( 1 ). 
     
     
       7. A method according to  claim 1 , characterised in that water that is supplied to the combustion chamber ( 15 ) or that is used for the generation of water steam is filtered in respect of particles after having been condensed from water steam in an exhaust gas system connected to the engine. 
     
     
       8. A method according to  claim 1 , characterised in that it is implemented by means of a control system ( 5 ) that comprises a computer program, which is arranged for the purpose of optimal alternation of combustion strokes and steam expansion strokes. 
     
     
       9. A method according to  claim 1 , characterised in that some of the steam expansion strokes are selected to mainly include a supply of water into the combustion chamber ( 15 ), and that the remaining steam expansion strokes are selected to mainly comprise a supply of water steam into the combustion chamber ( 15 ). 
     
     
       10. A method according to  claim 1 , characterised in that the supply of water or water steam is executed in connection to the end of an evacuation stroke. 
     
     
       11. A method according to  claim 9 , characterised in that the execution of steam expansion strokes that mainly comprise supply of water is based on the cylinder wall temperature, and so often that an over-heating of the cylinder or cylinders ( 1 ) of the engine is avoided. 
     
     
       12. A method according to  claim 11 , characterised in that the supply of water steam is executed when the steam pressure is so high that the work performed during the steam expansion stroke is mainly equal to the one of the other power strokes. 
     
     
       13. A combustion engine, comprising at least one cylinder ( 1 ), a reciprocating piston ( 16 ) that is arranged in the cylinder ( 1 ), a combustion chamber that is delimited by the cylinder ( 1 ) and the piston ( 16 ), and an electronic control system ( 5 ), and means ( 10 ) for injecting water or water steam into the combustion chamber ( 15 ), said control system ( 5 ) being arranged to control the means ( 10 ) for injecting water or water steam, such that power strokes that are mainly based on expanding combustion gases are alternated with power strokes that are mainly based on expanding water steam, water and/or water steam being supplied to the combustion chamber ( 15 ) in connection to the end of an evacuation stroke, characterised in that it comprises inlet and outlet valves ( 2 ,  3 ) that are controlled by the electronic control system ( 5 ), and that the inlet valves ( 2 ) to the combustion chamber ( 15 ) are arranged to close as a response to a signal from the control system ( 5 ) ordering water/water steam to be supplied to the combustion chamber ( 15 ). 
     
     
       14. A computer program product, stored on a readable computer program medium, for implementation of the method according to  claim 1 .